The Trump administration faces a stark choice this week over the war in Yemen in what could be a defining moment for the president’s foreign policy and U.S. ties with Middle Eastern allies.

Under a new law linking the actions of Persian Gulf countries to continued U.S. military support, Secretary of State Mike Pompeo is required to inform lawmakers by Wednesday whether he thinks Saudi Arabia and the United Arab Emirates are doing enough to protect noncombatants in the two countries’ war against Houthi rebels in Yemen.

Since the nations began a bombing campaign in 2015, the United States has provided limited aid to the operation, conducting aerial refueling for gulf warplanes, sharing intelligence and supplying partner militaries with sophisticated weaponry.

Now, aerial refueling is conditioned on the administration’s ability to attest that those nations are taking meaningful steps to end the war and contain a massive humanitarian crisis.

A decision to declare full support for the Saudi-led coalition is certain to ignite a torrent of criticism from opponents of the war. A decision to withhold backing, on the other hand, would be seen as a slap in the face to close U.S. allies. Either way, the administration must declare in categorical terms its position on a campaign that has made even the gulf nations’ most ardent supporters uncomfortable.

“The certification is an opportunity for the U.S. to give an honest assessment of the harm civilians are suffering in Yemen and the role the U.S. plays in supporting the Saudi-led coalition,” said Andrea Prasow, the deputy Washington director for Human Rights Watch, which has criticized Saudi Arabia’s conduct in the war.

Officials across the government have voiced support in the past week for continuing and even expanding U.S. assistance to the coalition. But others remain opposed to publicly backing the campaign at a time when its record has generated sharp controversy.

The deadline brings to a head an intense internal debate about the future of U.S. aid to the coalition. Officials across the government also have voiced exasperation over strikes that have killed dozens of Yemeni children in recent weeks, the latest in multiple attacks on civilian targets.

The humanitarian emergency in Yemen has left millions hungry and suffering from disease. Critics of the Saudi-led coalition say it has deepened the crisis by imposing severe restrictions at air and sea ports.

“We believe there is a moral imperative to do everything we can to ensure the Saudi-led coalition stops killing civilians,” Sens. Jeanne Shaheen (D-N.H.) and Todd C. Young (R-Ind.), who championed the new certification measure, said in an opinion piece in The Washington Post on Tuesday.

“If that does not happen, support for the coalition in Congress may reach a breaking point as the world’s worst humanitarian crisis deteriorates further,” they wrote.

Defenders of the coalition say the criticism overlooks abuses carried out by the Houthis and, with their links to Iran and frequent missile attacks on Saudi Arabia, the threat they pose to the region. A recent U.N. report said all parties could be guilty of war crimes.

If Pompeo does not endorse the gulf nations’ conduct, the administration would almost certainly use a waiver under the same law to allow military aid to continue. But even a decision to continue aid after that implicit rebuke could cause a rift with those allies at a time when the White House is seeking their support for a host of initiatives, including a new regional military alliance dubbed the “Arab NATO.”

It was not immediately clear if the administration would attempt to endorse some of the coalition's actions in Yemen but not others, and what the congressional response would be.

Since taking office, President Trump has strengthened U.S. ties with Saudi Arabia and the UAE. While his administration has criticized the coalition periodically for its handling of the war, it has restored arms sales suspended under President Barack Obama and echoed gulf concerns about the Houthis’ ties to Iran.

In an indication of that support, a senior administration official said the coalition’s investigation into an Aug. 9 strike that killed more than 40 children showed the coalition’s willingness to acknowledge mistakes, revise rules of engagement and hold personnel accountable. That, the official said, “is all evidence of progress that they’re continuing to make.”

The official, who like others spoke on the condition of anonymity to discuss internal deliberations, described a “Catch-22” surrounding U.S. assistance. “There’s a logical flaw in the argument that the Saudis aren’t as capable as the U.S. We want them to be as capable as the U.S., so we should withdraw assistance to compel them to increase their capability faster. That seems backwards,” the official said.

“One could argue that they are best positioned to improve their conduct when engaged, when provided advice and assistance,” he said.

Officials said the State Department had prepared a memo for Pompeo laying out options, from ending assistance to expanding it with the goal of ensuring more precise coalition air operations. It was expected that Pompeo would make a decision on the certification issue only this week.

“It’s an intense debate about what is a glaring problem about civilian casualties and whether we continue to work with the Saudis or whether we feel we have to put some distance” between the United States and the war, another official said. “A lot of us also feel that things are going to get worse if we’re not even involved.”

Officials at the Pentagon have consistently expressed support for continuing U.S. aid. But some lawmakers say even the current level of assistance could leave U.S. military personnel vulnerable to war-crimes allegations.

“I believe it harms our national security more to be part of the kill chain that results in children, women and men being killed,” said Rep. Ted Lieu (D-Calif.), a former Air Force lawyer. “It is a huge recruiting tool for terrorists.”